The cost of manufacturing automobiles is considerably greater in Esteria than in Burdistan. In order to stimulate Esterian consumers` purchases of domestically manufactured automobiles, the Esterian government has historically charged taxes on automobiles manufactured in Burdistan. Five years ago, however, the Esterian government dropped those taxes; in those five years, the number of workers employed in Esterian automobile factories has decreased by 30%. Therefore, the number of vehicles manufactured and sold in Esteria must have decreased in the last five years.
Which of the following, if true, most weakens the argument?
【选项】Many Esterian automobile manufacturers operate factories outside Esteria.